Oxaliplatin, cis-oxalato-(trans-L-1,2-cyclohexanediamine)-platinum (II) complex, has the following structure:

Oxaliplatin is slightly soluble in water at 6 mg/mL, very slightly soluble in methanol, and practically insoluble in ethanol and acetone.
Oxaliplatin is marketed as ELOXATIN™ (oxaliplatin for injection), available from Sanofi Aventis US, which is supplied in vials containing 50 mg or 100 mg of oxaliplatin as a sterile, preservative-free lyophilized powder for reconstitution (PDR®; Eloxatin for injection—Complete Monograph).
Oxaliplatin is an antineoplastic agent similar to cisplatin. It is given with fluorouracil and folinic acid in the treatment of metastatic colorectal cancer and in the adjuvant treatment of stage III (Dukes C) colon cancer.
U.S. Pat. No. 4,169,846 claimed oxaliplatin per se and its preparation by a process which yielded it in very low amounts. Improved methods for producing a mixture of trans-D- and trans-L-isomers of oxaliplatin were then disclosed in the patent literature, such as JP 09132583, EP 0625523, EP 0801070, U.S. Pat. No. 5,290,961, U.S. Pat. No. 5,298,642, U.S. Pat. No. 5,338,874 and EP 0567438. These methods involve the preparation of a dihalogen cis-platinum (II) complex of 1,2-diaminocyclohexane of formula (4),

wherein the dihalogen are Cl, Br or I,
which is converted to cis-diaquo-1,2-diaminocyclohexane platinum (II) complex of formula (3),

which is then reacted with oxalic acid or potassium oxalate to obtain the mixture of trans-D- and trans-L-isomers of oxaliplatin.
In EP 0567438, this process is described as a one-pot process, in which the compound of formula (4) is directly converted into the compound of formula (3), without its isolation.
An alternative synthetic route disclosed in EP 0625523 is through the reaction of dihalogen cis-platinum (II) complex of 1,2-diaminocyclohexane of formula (4), wherein the dihalogen are Cl or Br, with silver oxalate, followed by the removal of the silver chloride formed.
EP 0567438 further provides a high purity process to obtain oxaliplatin, where optical resolution of the D-isomer and L-isomer of cis-oxalato-(trans-D,L-1,2-cyclohexanediamine) Pt(II) is conducted by an HPLC method.
Another process for obtaining oxaliplatin is described in WO 2005/035544. This route of synthesis goes through diaquo-(1,2-cyclohexanediamine)Pt(II) of formula (3), in a lengthy process, which requires tedious workup in order to obtain the desired oxaliplatin in high purity.
There still remains a need for processes for the preparation of oxaliplatin, which produce optically pure oxaliplatin in improved and industrial methods.